$[<identifier>]
項目一覧
定義
$[<identifier>]
The filtered positional operator
$[<identifier>]
identifies the array elements that match thearrayFilters
conditions for an update operation, e.g.db.collection.updateMany()
anddb.collection.findAndModify()
.Used in conjunction with the
arrayFilters
option, the$[<identifier>]
operator has the following form:{ <update operator>: { "<array>.$[<identifier>]" : value } }, { arrayFilters: [ { <identifier>: <condition> } ] } Use in conjunction with the
arrayFilters
option to update all elements that match thearrayFilters
conditions in the document or documents that match the query conditions. For example:db.collection.updateMany( { <query conditions> }, { <update operator>: { "<array>.$[<identifier>]" : value } }, { arrayFilters: [ { <identifier>: <condition> } ] } ) 注意
<identifier>
は小文字で始まり、含めることができるのは英数字のみです。For an example, see Update All Array Elements That Match
arrayFilters
.
動作
MongoDB 5.0 以降、更新演算子では名前が文字列ベースのドキュメントフィールドを辞書順に処理します。数値名のフィールドは、数値順に処理されます。詳細については、「更新演算子の動作」を参照してください。
制限事項
The arrayFilters
option cannot include the following query
operators:
upsert
If an upsert operation results in an insert, the query
must
include an exact equality match on the array
field in order to use $[<identifier>]
in the update statement.
For example, the following upsert operation, which uses $[<identifier>]
in the update document, specifies an exact equality match condition
on the array field:
db.collection.updateOne( { myArray: [ 0, 1 ] }, { $set: { "myArray.$[element]": 2 } }, { arrayFilters: [ { element: 0 } ], upsert: true } )
If no such document exists, the operation would result in an insert of a document that resembles the following:
{ "_id" : ObjectId(...), "myArray" : [ 2, 1 ] }
If the upsert operation did not include an exact equality match and no matching documents were found to update, the upsert operation would error. For example, the following operations would error if no matching documents were found to update:
db.array.updateOne( { }, { $set: { "myArray.$[element]": 10 } }, { arrayFilters: [ { element: 9 } ], upsert: true } )
The operation would return an error that resembles the following:
MongoServerError: The path 'myArray' must exist in the document in order to apply array updates.
ネストされた配列
The filtered positional operator $[<identifier>]
can
be used for queries which traverse more than one array and nested arrays.
For an example, see Update Nested Arrays in Conjunction with $[]
.
例
Update All Array Elements That Match arrayFilters
students
コレクションを次のように作成します。
db.students.insertMany( [ { "_id" : 1, "grades" : [ 95, 92, 90 ] }, { "_id" : 2, "grades" : [ 98, 100, 102 ] }, { "_id" : 3, "grades" : [ 95, 110, 100 ] } ] )
To update all elements that are greater than or equal to 100
in the
grades
array, use the filtered positional operator
$[<identifier>]
with the arrayFilters
:
db.students.updateMany( { }, { $set: { "grades.$[element]" : 100 } }, { arrayFilters: [ { "element": { $gte: 100 } } ] } )
The positional $[<identifier>]
operator acts as a placeholder for
all elements in the array field that match the conditions specified in
arrayFilters
.
操作後、students
コレクションには次のドキュメントが含まれます。
{ "_id" : 1, "grades" : [ 95, 92, 90 ] } { "_id" : 2, "grades" : [ 98, 100, 100 ] } { "_id" : 3, "grades" : [ 95, 100, 100 ] }
Update All Documents That Match arrayFilters
in an Array
The $[<identifier>]
operator facilitates updates to arrays
that contain embedded documents. To access the fields in the embedded
documents, use the ドット表記 with the
$[<identifier>]
.
db.collection.updateMany( { <query selector> }, { <update operator>: { "array.$[<identifier>].field" : value } }, { arrayFilters: [ { <identifier>: <condition> } } ] } )
students2
コレクションを次のように作成します。
db.students2.insertMany( [ { "_id" : 1, "grades" : [ { "grade" : 80, "mean" : 75, "std" : 6 }, { "grade" : 85, "mean" : 90, "std" : 4 }, { "grade" : 85, "mean" : 85, "std" : 6 } ] }, { "_id" : 2, "grades" : [ { "grade" : 90, "mean" : 75, "std" : 6 }, { "grade" : 87, "mean" : 90, "std" : 3 }, { "grade" : 85, "mean" : 85, "std" : 4 } ] } ] )
To modify the value of the mean
field for all elements in the
grades
array where the grade is greater than or equal to 85
,
use the positional $[<identifier>]
operator and arrayFilters
:
db.students2.updateMany( { }, { $set: { "grades.$[elem].mean" : 100 } }, { arrayFilters: [ { "elem.grade": { $gte: 85 } } ] } )
操作後、コレクションには次のドキュメントが含まれます。
{ "_id" : 1, "grades" : [ { "grade" : 80, "mean" : 75, "std" : 6 }, { "grade" : 85, "mean" : 100, "std" : 4 }, { "grade" : 85, "mean" : 100, "std" : 6 } ] } { "_id" : 2, "grades" : [ { "grade" : 90, "mean" : 100, "std" : 6 }, { "grade" : 87, "mean" : 100, "std" : 3 }, { "grade" : 85, "mean" : 100, "std" : 4 } ] }
Update All Array Elements that Match Multiple Conditions
students3
コレクションを次のように作成します。
db.students3.insertMany( [ { "_id" : 1, "grades" : [ { "grade" : 80, "mean" : 75, "std" : 6 }, { "grade" : 85, "mean" : 100, "std" : 4 }, { "grade" : 85, "mean" : 100, "std" : 6 } ] }, { "_id" : 2, "grades" : [ { "grade" : 90, "mean" : 100, "std" : 6 }, { "grade" : 87, "mean" : 100, "std" : 3 }, { "grade" : 85, "mean" : 100, "std" : 4 } ] } ] )
To modify the value of the std
field for all elements in the
grades
array where both the grade is greater than or equal to
80
and the std
is greater than or equal to 5
, use the
positional $[<identifier>]
operator and arrayFilters
:
db.students3.updateMany( { }, { $inc: { "grades.$[elem].std" : -1 } }, { arrayFilters: [ { "elem.grade": { $gte: 80 }, "elem.std": { $gte: 5 } } ] } )
操作後、コレクションには次のドキュメントが含まれます。
{ "_id" : 1, "grades" : [ { "grade" : 80, "mean" : 75, "std" : 5 }, { "grade" : 85, "mean" : 100, "std" : 4 }, { "grade" : 85, "mean" : 100, "std" : 5 } ] } { "_id" : 2, "grades" : [ { "grade" : 90, "mean" : 100, "std" : 5 }, { "grade" : 87, "mean" : 100, "std" : 3 }, { "grade" : 85, "mean" : 100, "std" : 4 } ] }
Update Array Elements Using a Negation Operator
alumni
コレクションを次のように作成します。
db.alumni.insertMany( [ { "_id": 1, "name": "Christine Franklin", "degrees": [ { "level": "Master" }, { "level": "Bachelor" } ], }, { "_id": 2, "name": "Reyansh Sengupta", "degrees": [ { "level": "Bachelor" } ], } ] )
To modify all elements in the degrees
array that do not have
"level": "Bachelor"
, use the positional $[<identifier>]
operation with the $ne
query operator:
db.alumni.updateMany( { }, { $set : { "degrees.$[degree].gradcampaign" : 1 } }, { arrayFilters : [ {"degree.level" : { $ne: "Bachelor" } } ] } )
操作後、コレクションには次のドキュメントが含まれます。
{ _id: 1, name: 'Christine Franklin', degrees: [ { level: 'Master', gradcampaign: 1 }, { level: 'Bachelor' } ] }, { _id: 2, name: 'Reyansh Sengupta', degrees: [ { level: 'Bachelor' } ] }
Update Nested Arrays in Conjunction with $[]
The $[<identifier>]
filtered positional operator, in conjunction
with the $[]
all positional operator, can be used to update
nested arrays.
Create a collection students4
with the following document:
db.students4.insertOne( { "_id" : 1, "grades" : [ { type: "quiz", questions: [ 10, 8, 5 ] }, { type: "quiz", questions: [ 8, 9, 6 ] }, { type: "hw", questions: [ 5, 4, 3 ] }, { type: "exam", questions: [ 25, 10, 23, 0 ] }, ] } )
The following updates the values that are greater than or equal to
8
in the nested grades.questions
array if the associated
grades.type
field is quiz
.
db.students4.updateMany( {}, { $inc: { "grades.$[t].questions.$[score]": 2 } }, { arrayFilters: [ { "t.type": "quiz" }, { "score": { $gte: 8 } } ] } )
注意
Don't add spaces around the array identifiers. If you use
grades.$[ t ].questions.$[ score ]
in the previous example, the
example fails.
After the operation, the collection has the following document:
{ "_id" : 1, "grades" : [ { "type" : "quiz", "questions" : [ 12, 10, 5 ] }, { "type" : "quiz", "questions" : [ 10, 11, 6 ] }, { "type" : "hw", "questions" : [ 5, 4, 3 ] }, { "type" : "exam", "questions" : [ 25, 10, 23, 0 ] } ] }
To update all values that are greater than or equal to 8
in the
nested grades.questions
array, regardless of type
:
db.students4.updateMany( {}, { $inc: { "grades.$[].questions.$[score]": 2 } }, { arrayFilters: [ { "score": { $gte: 8 } } ] } )